Blood pump assembly having a sensor and a sensor shield

ABSTRACT

A blood pump assembly can include various components such as a housing and a sensor configured to detect one or more characteristics of the blood. In some embodiments, the sensor can be coupled to the housing and can include a sensor membrane configured to deflect in response to a change in a blood parameter (e.g., pressure). The blood pump assembly can include a shield that covers at least a portion of the sensor membrane so as to protect the sensor from damage when the blood pump assembly is inserted through an introducer and navigated through the patient&#39;s vasculature and/or when the blood pump assembly is inserted into the heart in a surgical procedure. One or more protective layers can be deposited over the sensor membrane to prevent the sensor membrane from being dissolved through interactions with the patient&#39;s blood.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/433,138, filed Jun. 6, 2019, now U.S. Pat. No. 11,027,114, which is acontinuation of U.S. patent application Ser. No. 15/615,259, filed Jun.6, 2017, now U.S. Pat. No. 10,342,906, which claims the benefit of U.S.Provisional Application No. 62/346,163, filed Jun. 6, 2016, thedisclosures of which are hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

A blood pump assembly, such as an intracardiac blood pump assembly, maybe introduced into the heart to deliver blood from the heart into anartery. Various blood pump assemblies pull blood from the left ventricleof the heart and expel blood into the aorta. Some blood pump assembliesmay support the left side of the heart and may be introducedpercutaneously during a cardiac procedure through the vascular system,such as by a catheterization procedure through the femoral artery, intothe ascending aorta, across the aortic valve, and into the leftventricle. In systems intended to support the right side of the heart,blood pump assemblies can be introduced through a vein and inserted intothe heart through the venous system (i.e. vena cava). Blood pumpassemblies for either side of the heart may also be surgically implantedor inserted through the subclavian and/or carotid arteries.

During insertion of a blood pump assembly through a blood vessel, thetorturous path and/or calcified anatomy can obstruct and damagecomponents of the blood pump assembly.

Damage to a blood pump assembly during insertion may require removal orreplacement of the blood pump assembly. Because the blood pump assemblyis designed for use in procedures that impact patient vitality, it isimportant that the blood pump assembly be capable of precise operationand delivery. Still further, it can be important to monitor thepatient's interactions with the blood pump assembly.

SUMMARY OF THE INVENTION

In one aspect, a blood pump assembly includes a blood pump housingcomponent, at least one input port and at least one outlet port, and asensor coupled to the blood pump housing component. The sensor includesa sensor membrane configured to deflect in response to a change in ablood parameter. The sensor is coupled to a transmission fiber. Theblood pump assembly includes a shield that covers at least a portion ofthe sensor membrane to protect the sensor from physical damage.

In some implementations, the shield includes a barrier bump positioneddistal relative to the sensor membrane. In certain implementations, theblood pump assembly further includes a sensor visor to protect thesensor from physical damage, the sensor visor extending in a distaldirection beyond the sensor membrane. In some implementations, thesensor visor extends into a visor notch formed in the barrier bump. Incertain implementations, the blood pump assembly further includes a capthat covers the visor notch. In some implementations, the sensor visoris attached to the barrier bump by adhesive or welding. In certainimplementations, the shield includes at least one protective layercovering a surface of the sensor membrane. In some implementations, thesensor membrane is recessed in a proximal direction relative to thesensor visor. In certain implementations, the shield includes a bloodaperture extending through the blood pump housing component andpositioned distal relative to the sensor membrane for washing the sensormembrane with blood.

In another aspect, a blood pump assembly includes a blood pump housingcomponent, a cannula assembly coupled to the blood pump housingcomponent, and a sensor coupled to the blood pump housing component. Thesensor includes a sensor membrane configured to deflect in response to achange in a blood parameter, and the sensor is coupled to a transmissionfiber. The blood pump assembly includes a passive protective mechanismfor protecting the sensor from damage when the blood pump assembly isinserted into a patient.

In some implementations, the passive protective mechanism includes abarrier positioned distal to the sensor membrane. In certainimplementations, the barrier protrudes from the blood pump housingcomponent. In some implementations, the barrier is composed of the samematerial as the blood pump housing component. In certainimplementations, the barrier has a smooth outer surface which contactsthe blood. In some implementations, the barrier has a radial heightapproximately equal to or greater than a radial height of the sensor. Incertain implementations, the blood pump assembly further includes one ormore protective layers deposited on a surface of the sensor membranefacing toward a distal end of the blood pump assembly. In someimplementations, the one or more protective layers include a singlelayer deposited over the sensor membrane and formed of a materialcapable of being deposited as a gel and curing. In certainimplementations, the one or more protective layers include a materialcapable of preventing the sensor membrane from being dissolved by achemical or biological reaction with blood. In some implementations, theone or more protective layers include a layer of silicone. In certainimplementations, the one or more protective layers include a metaloxide. In some implementations, the sensor membrane has a thickness of 2microns or less. In certain implementations, the sensor is positioned ina sensor bed in the blood pump housing component. In someimplementations, the sensor is an optical sensor that transmits opticalsignals. In certain implementations, the blood pump housing componenthas a substantially cylindrical and elongate shape.

In another aspect, a blood pump assembly includes a drive unit, animpeller blade, a blood pump housing component, a cannula assembly, anda sensor. The cannula assembly is coupled to the blood pump housingcomponent. The blood pump housing component includes a peripheral wallextending about a rotational axis of the impeller blade. The impellerblade is rotatably coupled to the drive unit. The sensor is coupled tothe peripheral wall of the blood pump housing component. The sensorincludes a sensor membrane configured to deflect in response to a changein a blood parameter. The sensor membrane is coupled to a transmissionfiber. The blood pump assembly includes a shield that covers at least aportion of the sensor membrane.

In some implementations, the shield includes a barrier bump positioneddistal relative to the sensor membrane and a sensor visor overhangingthe sensor membrane. In certain implementations, the sensor visorextends to the barrier bump. In some implementations, the sensor visorextends into a visor notch in the barrier bump. In some implementations,a cap covers the visor notch. In certain implementations, the sensorvisor is attached to the barrier bump by adhesive. In someimplementations, the shield includes a protective layer covering asurface of the sensor membrane. In certain implementations, the sensormembrane is recessed further below the sensor visor by a distanceapproximately equal to the thickness of the protective layer. In someimplementations, the shield includes a blood aperture extending throughthe peripheral wall of the blood pump housing component and positioneddistal relative to the sensor membrane for washing the sensor membrane.In certain implementations, the blood aperture is positioned between thesensor membrane and the barrier bump. In some implementations, thesensor visor extends over the blood aperture.

In another aspect, a blood pump assembly includes a drive unit, animpeller blade, a blood pump housing component, a cannula assembly, anda sensor. The cannula assembly is coupled to the blood pump housingcomponent. The blood pump housing component includes a peripheral wallextending about a rotational axis of the impeller blade. The impellerblade is rotatably coupled to the drive unit. The sensor is coupled tothe peripheral wall of the blood pump housing component. The sensorincludes a sensor membrane configured to deflect in response to a changein a blood parameter. The membrane is coupled to a transmission fiber.The blood pump assembly includes a sensor shield which may be configuredas a passive protective mechanism positioned distal relative to thesensor membrane.

In some implementations, the shield (for example, the passive protectivemechanism) positioned distal relative to the sensor membrane includes abarrier positioned distal relative to the sensor membrane. In certainimplementations, the shield (for example, the barrier) positioned distalrelative to the sensor membrane includes a barrier bump positioneddistal relative to the sensor membrane. The barrier bump may protrudefrom the peripheral wall of the blood pump housing component. In certainimplementations, the shield (for example, the barrier or barrier bump)is composed of the same material as the blood pump housing component. Insome implementations, the shield (for example, the barrier or barrierbump) has a smooth surface. In certain implementations, the shield (forexample, the barrier or barrier bump) is composed of stainless steel. Insome implementations, the shield (for example, the barrier or barrierbump) is electropolished or mechanically polished. In certainimplementations, the shield (for example, the barrier or barrier bump)has a height approximately equal to or greater than the height of thesensor. In some implementations, the shield (for example, the barrier orbarrier bump) has a visor notch configured to receive a sensor visoroverhanging the sensor membrane.

In certain implementations, the shield of the blood pump assemblyincludes a passive protective mechanism positioned such that the sensormembrane is positioned between the passive protective mechanism and theperipheral wall of the blood pump housing component. In someimplementations, the shield (for example, the passive protectivemechanism) positioned such that the sensor membrane is between theshield and the peripheral wall of the blood pump housing includes abarrier positioned such that the sensor membrane is between the barrierand the peripheral wall of the blood pump housing. In certainimplementations, the shield (for example, the barrier) positioned suchthat the sensor membrane is between the shield and the peripheral wallof the blood pump housing includes a sensor visor overhanging the sensormembrane. In some implementations, the sensor visor is stainless steel.In certain implementations, the sensor visor has a smooth surface. Insome implementations, the sensor visor includes a biocompatiblematerial. In certain implementations, the sensor visor is coated by abiocompatible material.

In another aspect, a blood pump assembly includes a drive unit, animpeller blade, a blood pump housing component, a cannula assembly, anda sensor. The cannula assembly is coupled to the blood pump housingcomponent. The blood pump housing component includes a peripheral wallextending about a rotational axis of the impeller blade. The impellerblade is rotatably coupled to the drive unit. The sensor is coupled tothe peripheral wall of the blood pump housing component. The sensorincludes a sensor membrane configured to deflect in response to a changein a blood parameter. The membrane is coupled to a transmission fiber.The blood pump assembly includes a sensor shield which may be configuredas a passive protective mechanism covering a surface of the sensormembrane.

In some implementations, the shield (for example, the passive protectivemechanism) covering the surface of the sensor membrane includes abarrier covering the surface of the sensor membrane. In certainimplementations, the shield (for example, the barrier) covering thesurface of the sensor membrane includes a protective layer deposited onthe surface of the sensor membrane. In some implementations, the sensormembrane faces toward a distal end of the blood pump assembly and theprotective layer deposited on the surface of the sensor membrane isdeposited on the surface of the sensor membrane facing toward the distalend of the blood pump assembly. In certain implementations, theprotective layer has a thickness approximately equal to 0.03 mm orgreater. In some implementations, the protective layer has a thicknessapproximately equal to 0.13 mm or greater. In certain implementations,the protective layer includes a material capable of being deposited as agel and hardening. In some implementations, the protective layerincludes a material capable of preventing the sensor membrane from beingdissolved by a chemical reaction with blood. In certain implementations,the protective layer includes silicone.

In another aspect, a blood pump assembly includes a drive unit, animpeller blade, a blood pump housing component, a cannula assembly, anda sensor. The cannula assembly is coupled to the blood pump housingcomponent. The blood pump housing component includes a peripheral wallextending about a rotational axis of the impeller blade. The impellerblade is rotatably coupled to the drive unit. The sensor is coupled tothe peripheral wall of the blood pump housing component. The sensorincludes a sensor membrane configured to deflect in response to a changein a blood parameter. The membrane is coupled to a transmission fiber.The blood pump assembly includes a sensor shield which may be configuredas one or more active protective mechanisms for the sensor membrane.

In some implementations, the shield (for example, the one or more activeprotective mechanisms) includes a mechanism for washing the sensormembrane, for example, a mechanism for washing the sensor membrane withblood. In some implementations, the mechanism for washing the sensormembrane includes one or more components such as a blood apertureextending through the peripheral wall of the blood pump housingcomponent and positioned distal relative to the sensor membrane. Incertain implementations, the peripheral wall of the blood pump housingcomponent includes a recess positioned distal relative to the sensormembrane. In some implementations, the recess is wider than the sensor.In certain implementations, the blood aperture is positioned in therecess. In some implementations, the blood aperture permits bloodflowing through the cannula assembly and into the blood pump housingcomponent to exit the blood pump housing component and wash the sensormembrane.

In some implementations, the peripheral wall of the blood pump housingcomponent includes one or more blood exhaust windows. In certainimplementations, the peripheral wall of the blood pump housing componentincludes a transmission fiber bed recessed within the peripheral wall ofthe blood pump housing component, the transmission fiber of the sensorpositioned in the transmission fiber bed. The transmission fiber is usedto transmit signals sensed by the sensor to a processor for detectingthe blood parameter. In some implementations, the sensor includes aglass ring positioned about the transmission fiber.

In certain implementations, the sensor membrane has a thickness of 2microns or less. In some implementations, the sensor membrane has athickness of 1.3 microns or less. In certain implementations, the sensoris positioned in a sensor bed in the peripheral wall of the blood pumphousing component. In some implementations, the blood pump housingcomponent includes a plurality of struts extending between the bloodexhaust windows. The transmission fiber bed may be positioned in a strutof the plurality of struts of the blood pump housing component. In someimplementations, the transmission fiber is coupled to the strut of theplurality of struts by an epoxy. The impeller blade may be positioned atleast in part in the blood pump housing component. In someimplementations, the blood pump housing component is coupled to thedrive unit at a first end and the blood pump housing component iscoupled to the cannula assembly at a second end opposite the first end.In certain implementations, the cannula assembly includes a blood inflowcage. In some implementations, the blood inflow cage includes aplurality of inlet openings. In certain implementations, a flexibleatraumatic extension (for example, a pigtail) is coupled to the bloodinflow cage.

In another aspect, a method of manufacturing a blood pump assemblyincludes coupling a sensor to a peripheral wall of a blood pump housingcomponent, rotatably coupling an impeller blade to a drive unit suchthat the peripheral wall of the blood pump housing component extendsabout a rotational axis of the impeller blade, and coupling a cannulaassembly to the blood pump housing component. The sensor includes asensor membrane configured to deflect in response to a change in a bloodparameter. The sensor membrane is coupled to a transmission fiber. Thesensor may include a sensor visor overhanging the sensor membrane.

In some implementations, the method further includes positioning asensor visor in a visor notch of a barrier bump protruding from theperipheral wall of the blood pump housing component. In certainimplementations, coupling the sensor to the peripheral wall of the bloodpump housing component includes affixing (for example, by an epoxy) thesensor to the peripheral wall of the blood pump housing component. Insome implementations, coupling the sensor to the peripheral wall of theblood pump housing component includes positioning the sensor into ablood recess in the peripheral wall of the blood pump housing component.In certain implementations, the blood pump housing component includes aplurality of blood exhaust windows and a plurality of struts extendingbetween the blood exhaust windows, and the blood recess is positioned ina strut of the plurality of struts in the blood pump housing component.In some implementations, the method further includes coupling a bloodinflow cage to the cannula assembly. In certain implementations, themethod further includes coupling a flexible atraumatic extension to theblood inflow cage. In some implementations, a protective layer isdeposited over a surface of the sensor membrane. In certainimplementations, a protective layer is deposited over a surface of thesensor membrane and the sensor membrane is recessed further below thesensor visor by a distance approximately equal to the thickness of theprotective layer.

The sensor detects one or more disturbances or properties of the blood(for example, a deflection caused by a pressure that is used todetermine a blood parameter signal). In some implementations, the sensoris a pressure sensor or flow rate sensor. In certain implementations,the sensor transmits its sensed signals optically. In someimplementations, the transmission fiber is an optical fiber. In certainimplementations, the drive unit is driven by an external motor.

In another aspect, a method of detecting blood pressure includes pumpingblood through a cannula assembly coupled to a blood pump housingcomponent and detecting a blood pressure of the blood pumped using anoptical pressure sensor coupled to the peripheral wall of the blood pumphousing component. The blood is pumped by an impeller blade positionedat least in part in the blood pump housing component. The impeller bladeis rotated by a drive unit coupled to the impeller blade. The blood pumphousing component includes a peripheral wall extending about arotational axis of the impeller blade. The optical pressure sensorincludes a sensor membrane configured to deflect in response to a changein pressure on the sensor membrane. The sensor membrane is coupled to anoptical fiber. The optical pressure sensor includes a sensor visoroverhanging the sensor membrane.

In some implementations, pumping blood includes pumping blood throughone or more blood exhaust windows in the blood pump housing component.In certain implementations, the method further includes washing thesensor membrane using blood flow through a blood aperture extendingthrough the peripheral wall of the blood pump housing component. Theblood aperture is positioned in a blood recess positioned in front ofthe sensor membrane of the optical pressure sensor. In someimplementations, the peripheral wall of the blood pump housing componentincludes a barrier bump protruding from the peripheral wall of the bloodpump housing component. The barrier bump is positioned in front of theblood recess, such that the blood recess is between the barrier bump andthe sensor membrane. In certain implementations, the method furtherincludes deflecting the blood flowing through the blood aperture using asensor visor extending from the optical pressure sensor over the sensormembrane and into a visor notch in the barrier bump. In someimplementations, the sensor membrane includes a glass material. Incertain implementations, the sensor membrane faces toward a distal endof the pump. In some implementations, the sensor membrane is less than 2microns thick. In some implementations, a protective layer is depositedover a surface of the sensor membrane. In certain implementations, aprotective layer is deposited over a surface of the sensor membrane andthe sensor membrane is recessed further below the sensor visor by adistance approximately equal to the thickness of the protective layer.

It should be appreciated that all combinations of the foregoing conceptsand additional concepts discussed in greater detail below (provided suchconcepts are not mutually inconsistent) are contemplated as being partof the inventive subject matter disclosed herein. In particular, allcombinations of claimed subject matter appearing at the end of thisdisclosure are contemplated as being part of the inventive subjectmatter disclosed herein. Moreover, certain concepts may be omitted ornot implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 is a side view of an exemplary catheter-based blood pump assemblyhaving a sensor and exemplary shielding features for protecting thesensor;

FIG. 2 is a top view of the blood pump assembly of FIG. 1 ;

FIG. 3 is a partial top view of the blood pump assembly of FIG. 1 ;

FIG. 4 is a magnified perspective view of the sensor mounted on anoutflow cage of the blood pump assembly of FIG. 1 ;

FIG. 5 is a magnified side view of the sensor and outflow cage of FIG. 4;

FIG. 6 is a magnified end view of the blood pump assembly of FIG. 4showing the impeller hub, impeller blade, and exemplary shieldingfeatures for protecting the sensor;

FIG. 7 is a magnified end view of the sensor and shielding features ofthe blood pump assembly of FIG. 4 ;

FIG. 8 is a perspective view of the blood pump assembly of FIG. 4showing a cap and cover which provide smooth transitions between theoutflow cage and the shielding features;

FIG. 9 is a side view of a sensing assembly for a catheter-based bloodpump assembly;

FIG. 10 is a partial side cross-sectional view of a sensing assembly fora catheter-based blood pump assembly;

FIG. 11 is a partial side cross-sectional view of another sensingassembly including an additional protective layer covering the sensormembrane;

FIG. 12 is a partial side cross-sectional view of another sensingassembly including an additional protective layer covering the sensormembrane;

FIG. 13 is a flow diagram of an exemplary process for manufacturing ablood pump assembly; and

FIG. 14 is a flow diagram of an exemplary process for detecting bloodpressure.

DETAILED DESCRIPTION

To provide an overall understanding of the blood pump assemblies,sensors, methods of manufacturing blood pump assemblies, and methods fordetecting blood parameters such as pressure or flow contemplated herein,certain illustrative embodiments will be described. Although theembodiments and features described herein are specifically described foruse in connection with blood pump assemblies that may be introducedpercutaneously during a cardiac procedure through the vascular system,it will be understood that all the components and other featuresoutlined below may be combined with one another in any suitable mannerand may be adapted and applied to other types of cardiac therapy andcardiac therapy devices.

The systems, methods, and devices described herein provide a blood pumpassembly including a sensor and a shield that protects the sensor fromphysical damage. The sensor may include a sensor membrane, which may befragile. The shield can enable the blood pump assembly and sensor totraverse torturous and/or calcified anatomy of the vascular system andremain operable, such as by protecting the sensor membrane. The shieldmay include one or more passive protective mechanisms, active protectivemechanisms, or a combination of both. Passive protective mechanisms mayinclude one or more barriers which protect the sensor membrane. As anexample, a sensor visor may prevent soft obstructions, such as valveleaves on a blood pump introducer, from contacting and damaging thesensor membrane. A barrier bump is another example of a passiveprotective mechanism and can be positioned distal relative to the sensormembrane. The barrier bump may deflect calcification or other obstacleswithin the vascular system and/or prevent the sensor membrane from beingdamaged when the pump changes direction during delivery of the pumpthrough the vasculature and into the heart. The shield may also includean additional protective layer (for example, a layer of silicone)covering the sensor membrane. As an example, this protective layer mayprevent the sensor membrane from being dissolved by chemical reactionswith a patient's blood without significantly influencing or interferingwith accurate detection of pressure. A mechanism for washing the sensormembrane is an example of an active protective mechanism for the sensor.For example, a blood aperture can be positioned adjacent to the sensormembrane and blood flowing through the aperture may wash the front endof the sensor membrane to prevent buildup or clotting of blood on thesurface of the sensor membrane.

FIG. 1 is a side view of an exemplary catheter-based blood pump assembly101 having a sensor 1020 and exemplary shielding features for protectingthe sensor 1020. FIG. 2 is a top view of the blood pump assembly 101,and FIG. 3 is a partial top view of the blood pump assembly 101. Asshown, the blood pump assembly 101 includes a cannula assembly 102, thesensor 1020, a catheter shaft 106, a flexible atraumatic extension (forexample, a pigtail) 108, a blood pump motor 110, a blood pump motorhousing 105, a blood pump housing component 103, a drive shaft 104, animpeller hub 113, a blood inflow cage 107, and a guidewire hole 141. Thepigtail extension 108 includes a curved portion 109. The blood inflowcage 107 includes one or more input ports 111. The interior of the bloodpump housing component 103 is contiguous with the interior of thecannula assembly 102. The cannula assembly 102 is coupled to the bloodpump housing component 103 and the blood pump housing component 103 iscoupled to the blood pump motor housing 105. The blood pump housingcomponent has a substantially cylindrical and elongate shape. The bloodpump motor 110 is housed in the blood pump motor housing 105. As analternative, in certain other implementations, the blood pump motor 110has an integrated housing such that the outer layer of the blood pumpmotor 110 is the blood pump housing 105.

As used herein, “distal” means in the direction in which the blood pumpassembly is inserted into a blood vessel, and “proximal” is opposite thedistal direction. For example, in FIG. 1 , the extension 108 is distalto the sensor 1020 and the catheter shaft 106 is proximal to the sensor1020.

The cannula assembly 102 includes the blood inflow cage 107, which ispositioned toward the distal end of the cannula assembly 102 oppositefrom the proximal blood pump housing component 103. The catheter shaft106 extends from the blood pump motor housing 105 at the proximal end ofthe blood pump assembly 101. The flexible atraumatic extension (forexample, pigtail) 108 extends distally from the blood inflow cage 107 atthe distal end of the blood pump assembly 101. The blood pump assembly101 may be configured as a pump for the left side of the heart or forthe right side of the heart.

The sensor 1020 may sense blood pressure, blood flow rate, and/or otherparameters. The sensor 1020 transmits its sensed signals to a transducersystem to convert the signal into the desired physical or medicalvariable including signal conditioning and data acquisition system forlinearization and calibration of the parameter. For example, the sensor1020 may be an optical pressure sensor that transmits optical signals oran electrical sensor.

The cannula assembly 102 provides at least one central lumen 114configured to facilitate blood flow therein. The cannula assembly 102includes a bend 112. In some embodiments, the bend 112 is 45°. Oneskilled in the art will appreciate that other configurations for thecannula assembly 102 are possible. In certain implementations beingdesigned for use in the right heart, the cannula assembly 102 can haveone or more bends and may have different and/or multiple bend radii toadapt to the needs of passage and final position of the cannula assembly102. In certain embodiments, the cannula assembly 102 need not have abend. In certain embodiments, the diameter of the cannula assembly 102is about equal to or greater than 9 Fr (3 mm). For example, the diameterof the cannula assembly 102 may be 9 Fr (3 mm), 10 Fr (3.33 mm), 11 Fr(3.67 mm), 12 Fr (4 mm), >12 Fr, or any other suitable diameter. In someembodiments, the diameter of the cannula assembly 102 is about equal toor less than 9 Fr (3 mm). For example, the diameter of the cannulaassembly 102 may be 8 Fr (2.67 mm), 7 Fr (2.33 mm), 6 Fr (2 mm), <6 Fr,or any other suitable diameter.

The drive shaft 104 transfers torque from the blood pump motor 110 tothe impeller hub 113. For example, a proximal end portion (not shown) ofthe drive shaft 104 can be coupled to a rotor of the blood pump motor110 and a distal end (not shown) of the drive shaft 104 can be coupledto the impeller hub 113. In some embodiments, a flexible drive cable, amagnetic clutch, and/or magnetic drive components transfer torque fromthe blood pump motor 110 to the impeller hub 113. In certainembodiments, the blood pump motor 110 can be positioned external to thepatient and configured to rotate the rotor of the blood pump motor 110when the blood pump assembly 101 is positioned in the patient's heart,and a drive shaft or drive cable can be coupled to the rotor of theblood pump motor 110. In such embodiments, the blood pump motor 110 isabsent from the blood pump motor housing 105. For those embodiments, theblood pump motor housing 105 is modified to reduce rigid diameter and/orlength of the pump.

The cannula assembly 102 also includes a blood inflow cage 107positioned toward an opposite end of the cannula assembly 102 than theblood pump housing component 103. The blood inflow cage 107 includes oneor more input ports 111. The blood pump assembly 101 is configured suchthat actuation of the blood pump motor 110 and the drive shaft 104rotates the impeller hub 113 (which may include an impeller blade notshown in FIGS. 1-3 ) and draws blood or other fluid into the bloodinflow cage 107 (or blood inlet manifold) through the one or more inputports 111. The blood received through the blood inflow cage 107 travelsthrough the cannula assembly 102 to the blood pump housing component103. The blood entering the blood pump housing component 103 isexhausted from the blood pump housing component 103 through windows orblood exhaust apertures (not shown in figure) in an outflow cage at aproximal end of the blood pump housing component 103. In someembodiments, the flow direction can be opposite as that of the devicesillustrated herein. In such embodiments, inflow of blood occurs at theside of the cannula assembly 102 which is connected to the blood pumphousing component 103 and outflow of blood occurs at the opposite sideof the cannula assembly 102. When placed in a patient, the blood pumpassembly 101 can pump blood from the left ventricle (via the bloodinflow cage 107) to the aorta (via the blood exhaust apertures). Theblood pump assembly 101 includes a catheter shaft 106 extending from theblood pump motor housing 105 at the proximal end of the blood pumpassembly 101. The catheter shaft 106 houses electrical connector cablesproviding power and control signals to the blood pump motor 110 andreceiving information from one or more sensors such as the sensor 1020,discussed further herein in accordance with particular embodiments. Insome embodiments, the catheter shaft 106 includes one or more lumens tofacilitate receipt of purge fluid and to be used as a conduit for atransmission fiber. In some embodiments, the interior of one or morelumens of the catheter shaft 106 is coated with apolytetrafluoroethylene (PTFE) lining, e.g., Teflon, over at least aportion of the one or more lumens' length. Because the PTFE lining has alow coefficient of friction, the transmission fiber moves more freelythrough the one or more lumens, and is easier to insert or retract asneeded.

The blood pump assembly 101 includes a flexible atraumatic extension 108(for example, a pigtail) extending from the blood inflow cage 107 at adistal end of the blood pump assembly 101. The extension 108 includes acurved portion 109. The extension 108 assists with stabilizing the bloodpump assembly 101 in the correct position, for example in the leftventricle. In certain embodiments, the extension 108 is configurablefrom a straight configuration to a partially curved configuration.Accordingly, the extension 108 may be composed, at least in part, of aflexible material.

FIGS. 4-8 show various views of the sensor 1020 mounted on the bloodpump assembly 101 of FIG. 1 . FIG. 4 is a magnified perspective view ofthe sensor 1020 mounted on an outflow cage 400 of the blood pumpassembly 101 of FIG. 1 . FIG. 5 is a magnified side view of the sensor1020 and the outflow cage 400 of FIG. 4 . FIG. 6 is a magnified end viewof the blood pump assembly 101 of FIG. 4 showing the impeller hub 113,impeller blade 140, and exemplary shielding features for protecting thesensor 1020. FIG. 7 is a magnified end view of the sensor 1020 andshielding features of the blood pump assembly 101 of FIG. 4 . FIG. 8 isa perspective view of the blood pump assembly 101 of FIG. 4 showing acap and cover which provide smooth transitions between the outflow cage400 and the shielding features. For clarity, the cannula assembly 102 isomitted from FIGS. 4-8 .

As shown, the blood pump assembly 101 can include a shield. The shieldmay include a sensor visor, a barrier bump, an additional protectivelayer (for example, a silicone layer), and/or a blood aperture. In FIGS.4-8 , for example, the shield includes a sensor visor 1022, a barrierbump 123, and a blood aperture 136. In FIGS. 4-8 , the blood pumpassembly 101 further includes a plurality of struts 127, one or moreoutput ports 125, a sensor bed 134, a transmission fiber 1024, a recess122, an impeller blade 140, and a transmission fiber bed 135. The bloodpump housing component 103 includes the outflow cage 400. The sensor1020 includes a sensor head 721 and a sensor membrane 1023. Inembodiments having both a barrier bump 123 and a sensor visor 1022, thebarrier bump 123 may include a mechanism for connecting to the sensorvisor 1022. For example, in FIGS. 4-8 , the barrier bump 123 includes avisor notch 124 that receives and holds a portion of the sensor visor1022 in a fixed position. The sensor 1020 is attached to the outflowcage 400 of the blood pump housing component 103. For example, in FIGS.4-7 , the sensor 1020 is coupled distal to one of the plurality ofstruts 127 of the outflow cage 400 of the blood pump housing component103 and sits in the sensor bed 134. Preferably, the sensor 1020 is notpositioned on one of the plurality of struts 127. For example, in someembodiments, the sensor 1020 is positioned on a portion of the outflowcage 400 distal to the struts 127 (e.g., 0.1 mm distal, 0.5 mm distal, 1mm distal, 2 mm distal, 5 mm distal, 1 cm distal or any other suitabledistance). Alternatively, the sensor 1020 can be positioned on the bloodinflow cage (e.g., blood inflow cage 107) or on the cannula (e.g.,cannula assembly 102).

The sensor membrane 1023 of the sensor 1020 is configured to deflect inresponse to changes in blood parameters, for example, changes inpressure, flow rate, fluid composition, and/or viscosity. The sensormembrane 1023 is preferably thin. In some embodiments, the sensormembrane 1023 is less than two microns thick. In some embodiments, thesensor membrane 1023 is composed of a fragile glass material such assilicon, silicon dioxide, or silicon nitride. Deflections of the sensormembrane 1023 are used to measure changes in blood parameters (forexample, blood pressure) at the blood pump assembly 101. Due to the bendradius constraints of the transmission fiber 1024, the sensor membrane1023 points forward towards the distal end of the blood pump assembly101. Deflections of the sensor membrane 1023 are sensed by the sensorhead 721 and transmitted to the transmission fiber 1024. Thetransmission fiber 1024 transmits the sensor's sensed signals to anoptical bench for signal evaluation. The transmission fiber 1024 canextend across various locations on the blood pump assembly 101 dependingon the location of the sensor 1020 relative to other components of theblood pump assembly 101. In FIG. 4 , the transmission fiber 1024 extendsalong one of the plurality of struts 127 of the blood pump housingcomponent 103, along the blood pump motor housing 105, and through thecatheter shaft 106 (not shown). In some embodiments, the transmissionfiber 1024 is coated with a protective coating, such as a polymer (forexample, polyimide). The transmission fiber 1024 is attached to theblood pump housing component 103. In FIG. 4 , for example, thetransmission fiber 1024 is positioned in the transmission fiber bed 135recessed in the outflow cage 400 of the blood pump housing component103. The measured blood parameters (for example, pressure) and changesin such parameters provide information regarding operation of the bloodpump assembly 101, the location of the blood pump assembly 101 (forexample, in pressure sensor embodiments, pressure differences areassociated with various locations in the heart), and vital signs of thepatient in response to placement and operation of the blood pumpassembly 101.

In embodiments with sensors that transmit sensed signals optically, thetransmission fiber 1024 is an optical fiber and the transmission fiber1024 extends to a light source. In such embodiments, the reflection oflight or resonant frequencies (e.g., in embodiments using the sensingprinciple of a Fabry-Perot resonator) within the sensor head 721 changesin response to changes in the position of the sensor membrane 1023 underdeflection in response to changes in blood parameters. Changes in thereflection of light or resonant frequencies are transmitted by thetransmission fiber 1024 from the sensor head 721 to an optical bench (orother suitable components configured to convert optically modulatedpressure signal into electrically calibrated or digital data which canbe stored and/or analyzed using software) for signal evaluation. Theoptical bench may be remote from the blood pump housing component 103,for example located outside of the body in a console or in a connector.In embodiments with sensors that sense pressure, the movement of thesensor membrane 1023 in response to changes in pressure on the surfaceof the sensor membrane 1023 is transmitted by the transmission fiber1024 to an optical bench or transducer for pressure determination. Thesensors may transmit sensed pressure signals optically, as discussedabove.

The barrier bump 123 is positioned in front of/distal to the sensormembrane 1023 to protect the sensor membrane 1023. The barrier bump 123protrudes from the outflow cage 400 of the blood pump housing component103. In some embodiments, the barrier bump 123 is composed of the samematerial as the blood pump housing component 103, such as stainlesssteel. The barrier bump 123 may be electropolished, mechanicallypolished, or otherwise processed in such a way that it provides smoothsurfaces that minimize thrombosis and blood flow shear stress. Inparticular, it is preferred that all surfaces of the barrier bump 123which will be in contact with blood be smooth so as to minimizethrombosis and blood flow shear stress. The sensor 1020 may includevarious other protective features. In embodiments having both a barrierbump 123 and a sensor visor 1022, such as the embodiment shown in FIGS.4-8 , the barrier bump 123 may include a visor notch 124 configured toreceive and hold the sensor visor 1022 in a fixed position. Othermechanisms could be employed for connecting the sensor visor 1022 to thebarrier bump 123, such as adhesive (for example, epoxy), welding, etc.

As shown, the sensor visor 1022 can be a shroud that extends over thesensor membrane 1023. In embodiments having both a barrier bump 123 anda sensor visor 1022, such as the embodiment shown in FIGS. 4-8 , thesensor visor 1022 may extend to the visor notch 124 in the barrier bump123. The sensor visor 1022 helps to direct or deflect flow of bloodexiting the blood pump housing component 103 through the blood aperture136. The sensor visor 1022 deflects blood to the sensor membrane 1023 ofthe sensor 1020 and out to the sides through the recess 122. In someembodiments, the sensor visor 1022 is composed of stainless steel. Thesensor visor 1022 may have a curved geometry. The sensor visor 1022preferably has smooth surfaces for some or all of its surfaces incontact with blood so as to prevent thrombosis. The sensor visor 1022may be composed, at least in part, of a biocompatible material and/ormay have a biocompatible material coating.

As discussed herein, a blood pump assembly 101 may be introducedpercutaneously during a cardiac procedure through the vascular system.For example, the blood pump assembly 101 can be inserted by acatheterization procedure through the femoral artery, into the ascendingaorta, across the valve, and into the left ventricle such that the bloodpump assembly 101 can provide support to the left side of the heart. Asnoted, introducing the blood pump assembly 101 through an introducerunit into the vascular system may include traversing torturousdirectional changes and a calcified anatomy in the vascular system. Thesensor 1020, and in particular the sensor membrane 1023, may be composedof sensitive or brittle components that may be easily damaged by thetorturous and calcified anatomy of the vascular system. The barrier bump123 and the sensor visor 1022 permit the sensor 1020 to traverse thetorturous and calcified anatomy of the vascular system and remainoperable. For example, the barrier bump 123 may protect the sensormembrane 1023 by deflecting upcoming obstacles presented bycalcification within the vascular system or changes in direction of thesensor 1020. As another example, the sensor visor 1022 may protect thesensor membrane 1023 by preventing soft obstructions, such as valveleaves on a blood pump introducer, from contacting and damaging thesensor membrane 1023. In embodiments having both a barrier bump 123 anda sensor visor 1022, such as the embodiment shown in FIGS. 4-8 ,obstacles deflected by the barrier bump 123 may ride over the sensorvisor 1022, thereby preventing the obstacles from contacting and/ordamaging the sensor membrane 1023.

The sensor membrane 1023 is positioned in the recess 122 and positionedadjacent to the blood aperture 136. The recess 122 is where bloodflowing from cannula assembly 102 is introduced to and directly orindirectly interacts with the sensor membrane 1023 so that the fluidpressure may be determined. In FIGS. 4-8 , blood can directly interactwith the sensor membrane 1023. In embodiments in which there are one ormore protective layers deposited over the sensor membrane 1023 (asdiscussed below in relation to FIGS. 11-12 ), blood indirectly interactswith the sensor membrane 1023. The recess 122 is configured to be widerthan the sensor 1020 so that the blood can easily flow away, for examplelaterally, from the sensor 1020, allowing for pressure equivalence withthe pressure on the outside of the outflow cage 400 of the blood pumphousing component 103. In some embodiments, the width of the recess 122is configured to be about equal to or less than the width of the sensor1020.

The blood aperture 136 can allow blood to flow toward the sensormembrane 1023 and then exit the blood pump housing component 103. In theillustrated embodiment, the blood aperture 136 is positioned distal tothe sensor membrane 1023 and the blood aperture 136 is in the recess122. The blood aperture 136 permits blood flowing through the cannulaassembly 102 to wash the front end of the sensor membrane 1023 toprevent buildup or clotting of blood on the surface of the sensormembrane 1023. As shown, the blood aperture 136 extends from theinterior of the blood pump housing component 103 into the recess 122.The blood aperture 136 also permits blood flowing from the cannulaassembly 102 into the blood pump housing component 103 to exit the bloodpump housing component 103 in a manner similar to the way that bloodexits the blood pump housing component 103 through the one or moreoutput ports 125. Blood exiting the blood pump housing component 103through the blood aperture 136 flows past the sensor membrane 1023 inthe recess 122. The blood aperture 136 may be approximately 250 micronsin diameter. In some embodiments, the diameter of the blood aperture 136is greater than 250 microns, for example, 275 microns, 300 microns, 325microns, 350 microns, >350 microns, or any suitable diameter. In otherembodiments, the diameter of the blood aperture 136 is less than 250microns, for example, 225 microns, 200 microns, 175 microns, 150microns, 125 microns, 100 microns, <100 microns, or any suitablediameter. In some embodiments the flow can be directed inwards. Incertain embodiments, the flow can be bidirectional and blood can enterand exit the blood aperture 136, washing the sensor membrane 1023. Theblood aperture 136 preferably has smooth surfaces for some or all of itssurfaces in contact with blood so as to prevent thrombosis. Inembodiments where the sensor 1020 and the sensor membrane 1023 arepositioned more distal than the positioning shown in FIGS. 4-8 , thelikelihood of clotting of blood increases and the blood aperture 136becomes more important. In other embodiments in which the sensor 1020and the sensor membrane 1023 are positioned more proximally than thepositioning shown in FIGS. 4-8 , it may not be necessary to have a bloodaperture 136, and instead the sensor membrane 1023 can be directly openwith the blood.

The sensor 1020 can be attached to the outflow cage 400 of the bloodpump housing component 103 (or other components of the blood pumpassembly 101, such as the inflow cage 107) in various ways. In FIG. 4 ,the sensor 1020 sits in the sensor bed 134, which is configured toreceive the sensor 1020 in a recessed position in the outflow cage 400of the blood pump housing component 103. The sensor bed 134 extendsdirectly into the recess 122 to provide and facilitate an interfacebetween the sensor membrane 1023 and the blood entering the recess 122through the blood aperture 136. In some embodiments, the sensor bed 134includes laser texturing strips to facilitate placement and holding ofthe sensor 1020 therein. In certain embodiments, the sensor bed 134includes potting and/or smoothing by the use of epoxy or silicone tosmooth structures in and/or around the sensor bed 134.

As shown in FIG. 5 , an opening/window 1025 allows blood exiting orentering the blood aperture 136 (shown in FIG. 4 ) to wash the sensormembrane 1023. The barrier bump 123 is structured to have a height thatis greater than the height (e.g. in a direction radially outward from acentral longitudinal axis extending through the blood pump assembly 101)of the sensor 1020 to raise the position of any obstacles encounteredduring insertion of the sensor 1020. The obstacles are then able to riseover and be diverted away from the sensor 1020 and in particular overthe sensor membrane 1023. For example, the obstacles can ride along thesensor visor 1022 without contacting the sensor membrane 1023. Thesensor 1020 is recessed in the outflow cage 400 of the blood pumphousing component 103 distal to one of the plurality of struts 127.Positioning the sensor 1020 more distal on the blood pump housingcomponent 103 than the position shown in FIG. 5 can help withrepositioning the blood pump assembly 101. In some embodiments, thesensor 1020 and/or the sensor visor 1022 may be coupled to the outflowcage 400 of the blood pump housing component 103 (or another componentof the blood pump assembly 101, such as the inflow cage 107) and thebarrier bump 123 with an adhesive, including but not limited to anepoxy, may be welded, or may be coupled together using other fixationtechniques known to persons skilled in the art.

The blood pump housing component 103 can house the drive shaft 104 whichcan be coupled to the blood pump motor 110 to permit axial rotation ofthe drive shaft 104. The drive shaft 104 is coupled to the impeller hub113 at a distal end portion of the drive shaft 104. The impeller hub 103is coupled to the impeller blade 140. The impeller blade 140 draws bloodthrough the cannula assembly 102 to create a highly viscous helical flowof blood, the blood exiting the blood pump housing component 103 througha plurality of blood exhaust windows 125 provided in the sidewall of theoutflow cage 400 of the blood pump housing component 103. In someembodiments, the exhaust windows are formed in walls of the cannulaassembly 102 instead of or in addition to being formed in the blood pumphousing component 103. The impeller blade 140 may be expandable orcompressible. The outflow cage 400 includes a plurality of struts 127positioned around the outflow cage 400. The plurality of struts 127separate the one or more output ports 125. At least one of the pluralityof struts 127 includes the transmission fiber bed 135 for thetransmission fiber 1024 and aligns to the sensor bed 134 and thetransmission fiber bed 135 (shown in FIG. 4 ) for housing the sensor1020 and the transmission fiber 1024, respectively.

In some embodiments, the blood pump assembly 101 includes featuresproviding smooth transitions over certain structures of the blood pumpassembly 101. As shown in FIG. 8 , a cap 1027 covers the visor notch 124(not visible in figure) when the sensor visor 1022 is properlypositioned. The cap 1027 may include an adhesive, epoxy, weld, or otherstructure or material that can hold the sensor visor 1022 in placeand/or provide a smooth transition across the barrier bump 123.Similarly, the sensor 1020 and/or the transmission fiber 1024 (notvisible) are coupled to the outflow cage 400 of the blood pump housingcomponent 103 through a cover 1028, which may include but is not limitedto a layer of epoxy providing a smooth transition across the sensor 1020as well as securing the sensor 1020 and the transmission fiber 1024 inplace. One skilled in the art will appreciate that various otherfeatures providing smooth transitions over certain structures of theblood pump assembly 101 are possible. Preferably, all surfaces of theblood pump assembly 101 that touch blood are smooth to minimizethrombosis and blood flow shear stress.

FIG. 9 is a side view of a sensing assembly 1900 for a catheter-basedblood pump assembly. The sensing assembly 1900 includes a sensor 1920, asensor visor 1922, a transmission fiber 1924, and a connector 1925. Thesensor 1920 includes a sensor head 1921 and a sensor membrane 1923. Thesensor head 1921 houses sensing components. The sensor visor 1922 may becomposed of a material including but not limited to stainless steel. Thetransmission fiber 1924 extends from the connector 1925 to the sensorhead 1921. In embodiments where the sensing assembly 1900 sensespressure and transmits sensed signals optically, the transmission fiber1924 optically couples the sensor head 1921, through the connector 1925,to a light source configured to send light to the sensor membrane 1923and the modulated signal back to the optical bench/transducer. Aspressure is applied to the sensor membrane 1923 under the high pressureand/or vacuum caused by the impeller blade (not shown in figure)rotating, the sensor membrane 1923 deflects, causing a change/modulationof the reflected light which is sent back from the sensor head 1921. Thechange in the light is detected on behalf of the opticalbench/transducer and the change in pressure is determined.

FIG. 10 is a partial side cross-sectional view of a sensing assembly2000 for a catheter-based blood pump assembly. The sensing assembly 2000includes a sensor 2020, a transmission fiber 2024, a jacket 2027, glue2028, and a sensor visor 2022. The sensor 2020 includes a sensor head2021, a sensor membrane 2023, and a temperature compensation portion2042. The sensor head 2021 includes a cavity 2040. The transmissionfiber 2024 ends in the proximal portion of the sensor head 2021 to whichit is coupled with low loss. The cavity 2040 in combination with thesensor membrane 2023 forms a Fabry-Perot resonator. To allow for theresonant measuring principle, both sides of the cavity 2040 aremanufactured to reflect light. As far as detection of the signal has tobe made possible, on one side, preferably the transmission fiber 2024side, partial reflection is realized, and preferably on the sensormembrane 2023 side, full reflection is realized. The temperaturecompensation portion 2042 is configured to prevent drift in sensedsignals due to temperature fluctuations. The temperature compensationportion 2042 is smaller in size than the sensor membrane 2023 and mayinclude silicon dioxide. The jacket 2027 is positioned about thetransmission fiber 2024 and may include a glass ring. The transmissionfiber 2024 is coupled to the sensor head 2021 by the glue 2028, whichmay be ultraviolet-curing epoxy. The sensor visor 2022 is configured toextend beyond a distal end of the sensor membrane 2023.

The shield for the blood pump assembly 101 can be configured in otherways. In FIGS. 11-12 , the shield includes an additional protectivelayer covering the sensor membrane. FIG. 11 is a partial sidecross-sectional view of another sensing assembly 1100 including anadditional protective layer covering the sensor membrane. As shown, thesensing assembly 1100 includes a sensor 1120, a transmission fiber 1124,a jacket 1127, glue 1128, a sensor visor 1122, and a thin layer 1102.The sensor 1120 includes a sensor head 1121, a sensor membrane 1123, anda temperature compensation portion 1142. The sensor head 1121 includes acavity 1140. The transmission fiber 1124 ends in the proximal portion ofthe sensor head 1121 to which it is coupled with low loss. The cavity1140 in combination with the sensor membrane 1123 forms a Fabry-Perotresonator. To allow for the resonant measuring principle, both sides ofthe cavity 1140 are manufactured to reflect light. As far as detectionof the signal has to be made possible, on one side, preferably thetransmission fiber 1124 side, partial reflection is realized, andpreferably on the sensor membrane 1123 side, full reflection isrealized. The temperature compensation portion 1142 is configured toprevent drift in sensed signals due to temperature fluctuations. Thetemperature compensation portion 1142 is smaller in size than the sensormembrane 1123 and may include silicon dioxide. The jacket 1127 ispositioned about the transmission fiber 1124 and may include a glassring. The transmission fiber 1124 is coupled to the sensor head 1121 bythe glue 1128, which may be ultraviolet-curing epoxy. The sensor visor1122 is configured to extend beyond a distal end of the sensor membrane1123. The thin layer 1102 is encapsulated over and covers the sensormembrane 1123, and protects the sensor membrane 1123 from damage due tothe flow of blood over the sensor membrane 1123. For example, the thinlayer 1102 can prevent the sensor membrane 1123 from being dissolved bya chemical reaction with the patient's blood. Additionally, the thinlayer 1102 impedes biological deposits from forming directly on thesensor membrane 1123.

The thin layer 1102 may include material capable of being deposited ontothe sensor membrane 1123 as a gel and curing. For example, the thinlayer 1102 may include silicone. In some embodiments, the thin layer1102 includes silicon oxide, oxide, metal, metal oxide (such as tantalumpentoxide (Ta₂O₅), titanium, or a titanium oxide), or any other coatingcommonly used in the processing of microelectromechanical systems (MEMS)or semiconductors. The thin layer 1102 can have a thickness of about 1micron. In some embodiments, the thin layer 1102 has a thickness greaterthan 1 micron. For example, the thin layer 1102 may have a thickness of2 microns, 3 microns, 4 microns, 5 microns, >5 microns, or any suitablethickness. In certain embodiments, the thin layer 1102 has a thicknessof less than 1 micron. For example, the thin layer 1102 may have athickness of 0.8 microns, 0.6 microns, 0.4 microns, 0.2 microns, <0.2microns, or any suitable thickness. In certain embodiments, theprotection layer could be several layers to serve as differentprotection barriers. For example, one layer could be a very thin layerof a metal oxide (such as tantalum pentoxide (Ta₂O₅), titanium, or atitanium oxide), silicon oxide, oxide, metal, or any other coatingcommonly used in the processing of MEMS or semiconductors, and anotherlayer could be an additional polymer protection layer such as a layer ofsilicone polymer. The very thin layer of metal/metal oxide could be, forexample, about 20 nanometers thick. In other embodiments, more than twolayers may be preferred to improve adhesion capabilities between thedifferent layers (i.e. silicon, metal, polymer) and provide the desiredprotection capability. Depending on the stiffness or drift behavior ofthe materials, different thicknesses might be considered. For materialswith stronger negative influence on the signal (e.g., damping, drift,nonlinearity), thin layers will be preferred. For soft protectivelayers, thicker layers might be preferred to improve the protectivefunction.

FIG. 12 is a partial side cross-sectional view of another sensingassembly 1200 including an additional protective layer covering thesensor membrane. The sensing assembly 1200 includes a sensor 1220, atransmission fiber 1224, a jacket 1227, glue 1228, a sensor visor 1222,and a layer 1202. The sensor 1220 includes a sensor head 1221, a sensormembrane 1223, and a temperature compensation portion 1242. The sensorhead 1221 includes a cavity 1240. The transmission fiber 1224 ends inthe proximal portion of the sensor head 1221 to which it is coupled withlow loss. The cavity 1240 in combination with the sensor membrane 1223forms a Fabry-Perot resonator. To allow for the resonant measuringprinciple, both sides of the cavity 1240 are manufactured to reflectlight. As far as detection of the signal has to be made possible, on oneside, preferably the transmission fiber 1224 side, partial reflection isrealized, and preferably on the sensor membrane 1223 side, fullreflection is realized. The temperature compensation portion 1242 isconfigured to prevent drift in sensed signals due to temperaturefluctuations. The temperature compensation portion 1242 is smaller insize than the sensor membrane 1223 and may include silicon dioxide. Thejacket 1227 is positioned about the transmission fiber 1224 and mayinclude a glass ring. The transmission fiber 1224 is coupled to thesensor head 1221 by the glue 1228, which may be ultraviolet-curingepoxy. The sensor visor 1222 is configured to extend beyond a distal endof the sensor membrane 1223.

The layer 1202 is encapsulated over and covers the sensor membrane 1223,and protects the sensor membrane 1223 from damage due to the flow ofblood over the sensor membrane 1223. For example, the layer 1202 canprevent the sensor membrane 1223 from being dissolved by a chemicalreaction with the patient's blood. Additionally, the layer 1202 impedesbiological deposits from forming directly on the sensor membrane 1223.In embodiments where the sensing assembly 1200 is a pressure sensor, thelayer 1202 transmits pressure from the blood to the sensor membrane 1223so that the blood pressure can be sensed. The layer 1202 may include amaterial capable of being deposited onto the sensor membrane 1223 as agel and curing. For example, the layer 1202 may include silicone. Thelayer 1202 has a thickness of about 0.13 mm. In some embodiments, thelayer 1202 has a thickness of about 0.13 mm or greater. For example, thelayer 1202 may have a thickness of 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm,0.18 mm, 0.19 mm, 0.2 mm, >0.2 mm, or any suitable thickness. In certainembodiments, the layer 1202 has a thickness of about 0.13 mm or less.For example, the layer 1202 may have a thickness of 0.12 mm, 0.11 mm,0.1 mm, 0.09 mm, 0.08 mm, 0.07 mm, 0.06 mm, 0.05 mm, <0.05 mm, or anysuitable thickness. The sensor membrane 1223 is recessed furtherrelative to the sensor visor 1222 in the proximal direction than thesensor membrane 1123 in the embodiment of FIG. 11 by a distanceapproximately equal to the thickness of the layer 1202. Recessing thesensor membrane 1223 further below the sensor visor 1222 can provideimproved protection from damage due to the flow of blood over the sensormembrane 1223. The sensing assembly 1200 can include any number ofadditional protective layers deposited over the sensor membrane 1223,for example, 1, 2, or 3 protective layers.

The sensing assembly 1200 can also include a gel (e.g., silicone gel) orother material proximal to the sensor membrane 1223 and can partially orfully fill the cavity 1240 to ensure that there is no blood ingress.This can prevent thrombosis in this area of the sensing assembly 1200and can also prevent damage to the sensing assembly 1200 as blood couldpotentially damage the transmission fiber 1224 and interfere with itsconnection with the sensor head 1221.

FIG. 13 is a flow diagram of an exemplary process 1300 for manufacturinga blood pump assembly. At Step 1302, a sensor (e.g., sensor 1020 in FIG.4 ) is coupled to a blood pump housing component (e.g., outflow cage 400of blood pump housing component 103 in FIG. 4 ), such as using epoxy.Coupling the sensor to the outflow cage of the blood pump housingcomponent may include positioning the sensor into a recess (e.g., recess122 in FIG. 4 ) in the blood pump housing component. Alternatively andas previously stated, the sensor can be coupled to a cannula assembly ofthe blood pump assembly. The sensor includes a sensor membrane (e.g.,sensor membrane 1023 in FIG. 4 ) configured to deflect in response tochanges in blood parameters, for example, changes in pressure, flowrate, fluid composition, or viscosity. The sensor membrane is coupled toa transmission fiber (e.g., transmission fiber 1024 in FIG. 4 ). Thesensor includes a sensor visor (e.g., sensor visor 1022 in FIG. 4 )extending over the sensor membrane. One or more protective layers (e.g.,thin layer 1102 in FIG. 11 ) may be deposited over the sensor membraneto protect the sensor membrane from damage due to the flow of blood overthe sensor membrane. For example, the protective layer can prevent thesensor membrane from being dissolved by a chemical reaction with thepatient's blood. Additionally, the protective layer can impedebiological deposits from forming directly on the sensor membrane.Alternatively, the protective layer may be thicker than the thin layer1102 in FIG. 11 (e.g., layer 1202 in FIG. 12 ) and the sensor membranemay be recessed further below the sensor visor by a distanceapproximately equal to the thickness of the layer. Recessing the sensormembrane further below the sensor visor can provide improved protectionfrom damage due to the flow of blood over the sensor membrane.

At Step 1303, an impeller hub and blade (e.g., impeller hub 113 andimpeller blade 140 of FIG. 6 ) are coupled to a drive shaft (e.g., driveshaft 104 of FIG. 8 ) such that the impeller hub and impeller bladerotate as the drive shaft rotates. Alternatively, the impeller hub,blade, and drive shaft can be monolithic and integrally formed. Theoutflow cage of the blood pump housing component may include one or moreoutput ports (e.g., output ports 125 of FIG. 5 ) and a plurality ofstruts (e.g., struts 127 in FIG. 5 ) extending between the one or moreoutput ports. The recess may be positioned distal to one of the strut ofthe plurality of struts in the outflow cage of the blood pump housingcomponent.

At Step 1304, a cannula assembly (e.g., cannula assembly 102 in FIG. 1 )is coupled to the blood pump housing component. At Step 1306, the sensorvisor is positioned in a visor notch of a barrier bump (e.g., visornotch 124 of barrier bump 123 in FIG. 4 ) which protrudes from theoutflow cage of the blood pump housing component. The barrier bump andthe sensor visor provide advantages to the sensor in connection withpermitting the sensor to traverse the torturous and calcified anatomy ofthe vascular system and remain operable. At Step 1310, a blood inflowcage (e.g., blood inflow cage 107 of FIG. 1 ) is coupled to the cannulaassembly. At Step 1312, a flexible atraumatic extension (e.g., flexibleatraumatic extension 108 of FIG. 1 ) is coupled to the blood inflowcage.

FIG. 14 is a flow diagram of an exemplary process 1400 for detectingblood pressure. At Step 1402, blood is pumped through a cannula assembly(e.g., cannula assembly 102 in FIG. 1 ) using an impeller blade (e.g.,impeller blade 140 in FIG. 6 ) positioned at least in part in the bloodpump housing component (e.g., blood pump housing component 103 in FIG. 1). The impeller blade is coupled to an impeller hub (e.g., impeller hub113 of FIG. 6 ) rotated by a drive shaft coupled to the impeller hub.The blood pump housing component includes an outflow cage (e.g., outflowcage 400 in FIG. 4 ). Pumping blood may include pumping blood throughone or more output ports (e.g., output port 125 in FIG. 4 ) in the bloodpump housing component.

At Step 1403, blood pressure of the pumped blood is detected using anoptical pressure sensor (e.g., sensor 1020 in FIG. 4 ) coupled to theoutflow cage of the blood pump housing component. The optical pressuresensor includes a sensor membrane (e.g., sensor membrane 1023 in FIG. 4) configured to deflect in response to a change in pressure on thesensor membrane. The sensor membrane may include a glass/siliconmaterial. The sensor membrane may be facing toward a distal end of theblood pump assembly. The sensor membrane may have a thickness aspreviously described. The optical pressure sensor includes a sensorvisor (e.g., sensor visor 1022 in FIG. 4 ) extending a distance in thedistal direction beyond the sensor membrane so as to form a shroudportion overhanging the sensor membrane. The outflow cage of the bloodpump housing component may include a barrier bump (e.g., barrier bump123 in FIG. 4 ) protruding from the outflow cage of the blood pumphousing component. The barrier bump and the sensor visor provideadvantages to the optical pressure sensor in connection with permittingthe optical pressure sensor to traverse the torturous and calcifiedanatomy of the vascular system and remain operable. The barrier bump mayprotect the sensor membrane by deflecting upcoming obstacles presentedby calcification within the vascular system or changes in direction ofthe sensor. The sensor visor may protect the sensor membrane bypreventing soft obstructions, such as valve leaves on a blood pumpintroducer, from contacting and damaging the sensor membrane. Obstaclesdeflected by the barrier bump may ride over the sensor visor, therebypreventing the obstacles from contacting and/or damaging the sensormembrane. The barrier bump may be positioned in front of a recess (e.g.,recess 122 in FIG. 4 ). The recess may be between the barrier bump andthe sensor membrane.

A protective layer (e.g., thin layer 1102 in FIG. 11 ) or layers may bedeposited over the sensor membrane to protect the sensor membrane fromdamage due to the flow of blood over the sensor membrane. For example,the layers can prevent the sensor membrane from being dissolved by achemical or biological reaction with the patient's blood. Additionally,the layer can impede biological deposits from forming directly on thesensor membrane. Alternatively, the protective layer may be thicker thanthe thin layer 1102 in FIG. 11 (e.g., layer 1202 in FIG. 12 ) and thesensor membrane may be recessed further below the sensor visor by adistance approximately equal to the thickness of the layer. Recessingthe sensor membrane below the sensor visor can provide improvedprotection from damage due to the flow of blood over the sensormembrane. In the case of an optical sensor, the sensor is coupleddirectly or indirectly to an optical fiber (e.g., transmission fiber1024 in FIG. 4 ).

At Step 1404, the sensor membrane is washed by blood flowing through ablood aperture (e.g., blood aperture 136 of FIG. 4 ) extending throughthe outflow cage of the blood pump housing component. Washing the sensormembrane prevents buildup or clotting of blood on the surface of thesensor membrane.

At Step 1406, blood flowing through the blood aperture is deflectedusing the sensor visor which can extend from the optical pressure sensorover the sensor membrane and into a visor notch in the barrier bump. Theblood can also exit through the blood aperture and a new volume of bloodcan enter the blood aperture.

The foregoing is merely illustrative of the principles of thedisclosure, and the systems, methods, and devices can be practiced byother than the described embodiments, which are presented for purposesof illustration and not of limitation. It is to be understood that thesystems, devices, and methods disclosed herein, while shown for use inblood pump assemblies that may be introduced percutaneously during acardiac procedure through the vascular system, may be applied tosystems, devices, and methods to be used in other types of therapy anddevices requiring sensors.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

The invention claimed is:
 1. A blood pump assembly comprising: a driveunit; an impeller blade rotatably coupled to the drive unit; a bloodpump housing component including a peripheral wall extending about arotational axis of the impeller blade; a cannula assembly coupled to theblood pump housing component; a sensor coupled to the peripheral wall ofthe blood pump housing component, the sensor including a sensor membraneconfigured to deflect in response to a change in a blood parameter, thesensor membrane being coupled to a transmission fiber; and a shieldconfigured as one or more protective mechanisms for the sensor membrane,wherein the shield includes a mechanism for washing the sensor membrane.2. The blood pump assembly of claim 1, wherein the shield includes amechanism for washing the sensor membrane with blood.
 3. The blood pumpassembly of claim 1, wherein the shield includes a blood apertureextending through the blood pump housing component and positioned distalrelative to the sensor membrane.
 4. The blood pump assembly of claim 3,wherein the blood aperture has smooth surfaces to prevent thrombosis. 5.The blood pump assembly of claim 3, wherein the peripheral wall of theblood pump housing component includes a recess.
 6. The blood pumpassembly of claim 5, wherein the blood aperture is positioned in therecess.
 7. The blood pump assembly of claim 6, wherein the bloodaperture is positioned in front of the sensor membrane.
 8. The bloodpump assembly of claim 5, wherein the recess is wider than the sensor.9. The blood pump assembly of claim 1, wherein the sensor membrane has athickness of about 2 microns or less.